In graduate school at the University of Kansas, Kim contemplated her research topic. She wanted to study the evolution of a complex trait in birds (while traveling to exotic locations, of course!), but didn't know what would fit the bill. When her advisor told her about a strange tropical bird that made a buzzing noise with its wings, her curiosity leapt into action.

At the time, no one knew how the club-winged manakin made its mechanical hum, so Kim's studies began with alcohol-preserved manakins (which Kim fondly refers to as "pickled birds"). She dissected the wings of the club-winged manakin and compared their feathers, muscles, and bones to the homologous structures in other birds. Homologous structures are those that owe their similarity to inheritance from a common ancestor. By comparing homologous structures in various closely related species, Kim hoped to identify the unique features that had evolved in the club-winged manakin's lineage that allowed it to produce its strange noise.

Kim noticed some distinctive features of the club-winged manakin's wings, including odd feathers, stocky bones, and unusually heavy musculature. Although these structures had been noted before, and had even made an appearance in Darwin's book on sexual selection, they had never been formally described. They were obviously different from homologous structures in non-humming manakins, but to figure out how they actually worked, Kim needed to see them in action …